by Li-Hwa Lin and Robert G. Dean ; prepared for Pinellas County and Division of Beaches and Shores, Florida Department of Natural Resources.

General Note:

"March, 1989."

Funding:

This publication is being made available as part of the report series written by the faculty, staff, and students of the Coastal and Oceanographic Program of the Department of Civil and Coastal Engineering.

16. Abstract
This study presents the post-nourishment survey results for the Sand Key Phase II
beach nourishment project carried out in June, 1988. The monitoring program to this
beach nourishment project is a joint effort between the University of South Florida
and University of Florida. The field surveys include a total of 26 profiles,
encompassing approximately 3 miles of shoreline extending from DNR R-96 to R-111.
The total calculated volume loss of sand in the nourished segment (from R-99G to
R-107) between the July and November surveys is 49,215 cubic yards, which is a loss
about 9.3 percent of 529,150 cubic yards actually placed in the nourishment project.
The total loss of sand computed in the entire survey area is 18,305 cubic yards,
which is only 3.5 percent of the sand placed in the nourishment project. It is
stressed that a part of these net volume reductions is due to the background
erosion and not due to spreading losses induced by the nourishment project.

This is the third of a series of reports presenting offshore survey results for
the Sand Key Phase II beach nourishment project carried out in June, 1988. This
project comprised the placement of 369,714 cubic yards of sand (paid yardage) ob-
tained from Johns Pass ebb tidal shoals, delivered by pipeline dredge and placed
along 1.6 miles of Sand Key shoreline. As shown in Figure 1, the monitoring
project encompasses approximately 3 miles of shoreline extending from Florida
Department of Natural Resources (FDNR) Monument No. R-96 to FDNR Mon-
ument No. R-111.

This field program to document the performance of this beach nourishment
program is a joint effort between the University of South Florida (USF) and the
University of Florida (UF). The USF has presented their results in a series of three
reports.

This report is organized as follows. The main body of this report describes
the survey methods, problems encountered and any necessary adjustments to the
survey data. The following section presents an analysis of volume changes of sand
for the entire survey region at North Redington Beach and Redington Shores.
The volumes as determined by the November survey are compared with the post-
nourishment (July 88) surveyed volumes, providing a measure of project perfor-
mance over this four month period. The final section of the main body describes
the wave data from the Clearwater gage which is maintained by the Univeristy
of Florida. Appendix I presents the combined USF and UF profiles for the sec-
ond post-nourishment (Nov 18-23, 1988) survey. Appendix II presents, for each
profile line, the profiles obtained from the first (July 88) and second (Nov 88)
post-nourishment surveys. Appendix III presents the wave data obtained in Au-
gust, September, October, and November, 1988, from the UF maintained gage off
Clearwater. The digitized data for this and the two earlier surveys in the form of
floppy disks have been forwarded to Pinellas County and the Division of Beaches
and Shores of the Florida Department of Natural Resources.

The change in sand volume of the nourished beach was computed based on
the first (July 88) and second (Nov 88) post-nourishment surveys. The change is
a loss of 18,305 cubic yards between profiles R-96 and R-111G, which is a loss of
about 3.5 percent of 529,150 cubic yards, the total amount of sand actually placed
in the nourishment project. The loss within the nourished area (R-99G to R-107)
is 49,215 cubic yards, amounting to approximately 9.3 percent.

PURPOSE

The main objective of the project is to develop and interpret survey data.
Based upon the surveyed profile data, changes in sediment volumes along the
shoreline can be computed. At the end of the two year project the littoral sediment
budget in the North Redington Beach and Redington Shores can be evaluated.
Therefore, the long-term shoreline changes and sand losses for the project area can
be estimated. Also, by using this information and the wave information collected
from the Clearwater wave gage, a wave refraction study of the monitored project
area will be performed. The wave refraction study will allow comparison between
predicted and measured performances of the beach nourishment project. It can
be used also to interpret the sediment motion between any two surveyed profiles.

SURVEY AND REPORT SCHEDULE

The monitoring study is for a duration of two years plus pre- and post-
nourishment surveys. The offshore profiles were taken immediately prior to the
nourishment project and immediately upon completion of the nourishment. Off-
shore profiles are to be taken at three month intervals for the first twelve months.
During the second year after the initial nourishment, profiles will be taken at six
month intervals. Individual reports have been completed for the pre-nourishment
and first post-nourishment surveys. A report will be prepared for each additional
post-nourishment survey.

FIELD METHODOLOGY

The field survey program includes a total of 26 profiles. The corresponding
profile azimuths were established by USF for the pre-nourished beaches represent-
ing an approximate shore normal direction at that time (also see Figure 1). The
profiles are located at the U.S. Army Corps of Engineers profile points which are
D.N.R. reference monuments listed in Table 1. These profile lines include R-96,
R-97, R-98A, R-99A, T100, T100A, R101, R101A, R102, R103, R103A, T104,

L

TABLE 1: MONUMENTS INCLUDED IN SURVEY PROGRAM
State Plane Coordinates (from D.N.R.)

The change in sand volume of the nourished beach was computed based on
the first (July 88) and second (Nov 88) post-nourishment surveys. The change is
a loss of 18,305 cubic yards between profiles R-96 and R-111G, which is a loss of
about 3.5 percent of 529,150 cubic yards, the total amount of sand actually placed
in the nourishment project. The loss within the nourished area (R-99G to R-107)
is 49,215 cubic yards, amounting to approximately 9.3 percent.

PURPOSE

The main objective of the project is to develop and interpret survey data.
Based upon the surveyed profile data, changes in sediment volumes along the
shoreline can be computed. At the end of the two year project the littoral sediment
budget in the North Redington Beach and Redington Shores can be evaluated.
Therefore, the long-term shoreline changes and sand losses for the project area can
be estimated. Also, by using this information and the wave information collected
from the Clearwater wave gage, a wave refraction study of the monitored project
area will be performed. The wave refraction study will allow comparison between
predicted and measured performances of the beach nourishment project. It can
be used also to interpret the sediment motion between any two surveyed profiles.

SURVEY AND REPORT SCHEDULE

The monitoring study is for a duration of two years plus pre- and post-
nourishment surveys. The offshore profiles were taken immediately prior to the
nourishment project and immediately upon completion of the nourishment. Off-
shore profiles are to be taken at three month intervals for the first twelve months.
During the second year after the initial nourishment, profiles will be taken at six
month intervals. Individual reports have been completed for the pre-nourishment
and first post-nourishment surveys. A report will be prepared for each additional
post-nourishment survey.

FIELD METHODOLOGY

The field survey program includes a total of 26 profiles. The corresponding
profile azimuths were established by USF for the pre-nourished beaches represent-
ing an approximate shore normal direction at that time (also see Figure 1). The
profiles are located at the U.S. Army Corps of Engineers profile points which are
D.N.R. reference monuments listed in Table 1. These profile lines include R-96,
R-97, R-98A, R-99A, T100, T100A, R101, R101A, R102, R103, R103A, T104,

L

T104, R105, R105A, T106, T106A, R107, R107A, R108, R109, R110, and R111.
For all these profiles, the D.N.R. monuments serve as the baseline points for the
survey except for profiles R-102, R-105, and R-108 where the 'G' monuments es-
tablished on the gulf front seawall by the University of South Florida are used as
the baseline points.

The field surveys are divided into a landward portion (conducted by USF) and
a gulfward portion (conducted by UF).

Landward Portion of Profile

The technique of documenting the landward portion of the profiles has been
described in earlier USF reports, but will be presented briefly here.

The survey procedures for the landward portion of the profile are standard for
land surveying. Basically a leveling rod is held vertical at points of interest by a
'rod-person' and in this case the elevation is read using a transit. The distance
from the transit to the rod is established optically by reading stadia hairs on the
telescope of the transit. This procedure is continued out to wading depth where
the boat surveys continue the profile line into the gulf. In order to obtain the
maximum possible overlap between the landward and gulfward portions of the
lines, it is desirable to conduct the landward surveys at low tide and the gulfward
surveys during high tide.

Gulfward Portion of Profile

The offshore profile survey is performed using a computer controlled survey
system installed on a 26 feet aluminum power boat. The survey system includes a
fathometer unit (Model 412 Auto Track) and a range finder (Mini-Ranger Falcon
484). The fathometer is able to measure water depths ranging from 2.0 to 999.9
feet and provides an accuracy within 0.1 foot. The range finder can measure
distance between the receiver transmitter located on the boat and a microwave
transponder located on shore up to distances of 10 nautical miles with a probable
error range of 6 feet. When sampling a profile, the boat moves relatively slowly
along the profile in order to obtain dense data points. In the shallower water
depths, a boat speed of 4 knots is maintained and in deeper water where the
bottom slopes are less, a speed of 6 knots is maintained. The measured profile
data obtained from the fathometer and the range finder are recorded in a PDP-
11/23 Micro-computer at a sampling rate of one data point per second. Therefore,
the horizontal distance between any two contiguous sample points is about 7 feet
in the nearshore area, and 10 feet in the offshore area.

The Mini-Ranger which is used for horizontal positioning consists of a 'master'
unit mounted on the boat and a 'slave' unit located on the shore reference point
from which the profile is being measured. Upon command from the master unit
(at one second intervals), the slave unit responds and the delay between command
and receipt of response is interpreted as distance. Since only one transponder is
utilized, thus providing distance from the reference point, the alignment along
the profile is provided by positioning two large orange-color target boards on the
beach. They are separated by some distance and aligned with the profile azimuth
by using a transit. The boat then moves in a course adjusted visually on line with
the two target boards. Two survey runs are usually carried out for each profile line.
An extra run may be added to profile surveys if any irregularities of the survey
system are encountered during the profiling processes. For the post-nourishment
survey conducted in November, 1988, the profile surveys were extended gulfward
to a water depth of 18 feet.

Difficulties Encountered in the Surveys

For the pre-nourishment (May 88) and the first post-nourishment (July 88)
surveys, overlap of the landward and gulfward portions of some of the profiles was
not obtained, thus leaving an unsurveyed gap. Inspection of this problem showed
that greater emphasis needed to be given to carrying out the landward portion of
the surveys at low tide and the gulfward portion of the surveys at high tide. The
technique was refined for the gulfward portion of the profile lines so that the effort
during high tides is directed toward the critical inshore portion of these lines with
survey of the deeper offshore portion possible during any stage of the tide. This
offshore profile survey technique was first utilized in the November, 1988 survey
and proved effective and thus will be used in the sequent surveys.

ANALYSIS AND PRESENTATION OF DATA

The offshore profile data obtained in the field are analyzed in the Coastal
Laboratory of the Department of Coastal and Oceanographic Engineering at the
University of Florida. After the data are retrieved from the field, they are trans-
ferred from the PDP-11 Micro-computer to a standard VAX-750 computer for
later analysis. The first step in the analysis of surveyed profile data is to elimi-
nate any erratic points in the depth measurements with frequencies smaller than
0.1 Hz by utilizing a nine-point rectangular filter. The second step is to adjust
the water depth data, based upon the measurements of daily tides from a tide
gage, to N.G.V.D datum. The third step is to reformat the data based on a linear
interpolation to generate profile data points at spacings of 10 feet in horizontal
distance from the baseline. The fourth step is to blend the two or three runs of

a profile into one single profile. The reduced data indicate the final form for the
surveyed profiles and are available in 5.25" floppy diskettes at the Department of
Coastal and Oceanographic Engineering, University of Florida.

Appendix I presents plots combining the offshore profiles and beach profiles,
surveyed by the Department of Geology, University of South Florida, for the post-
nourishment survey. Appendix II presents the offshore and beach profiles for both
the first (July 88) and second (Nov 88) post-nourishment surveys. Some of the
composite profiles are seen to have a segment which is dashed in the nearshore
area. The dashed line indicates the 'constructed' profile which is not available
from either the beach/nearshore profile survey or the offshore profile survey. It is
constructed in a sense that if no bar formation is present in the adjacent profiles
a simple interpolation is then inserted for the gap. Otherwise, a smoothed bar
segment similar to the neighboring profiles is established in the gap. The offshore
profile for R-96 was not measured for this post-nourishment survey and was taken
as the same as the one surveyed in January, 1989. The comparison of profiles
T-104 between July and November surveys reveals large deviation of the two for
offshore distances greater than 2,600 feet. It is noted here that offshore portion
of T-104 was not measured in July, and it was linearly interpolated between the
two adjacent profiles: R-103A and T-104A. Thus, the interpolated T-104 profile
of July is less accurate than the measured one of November.

CALCULATION OF VOLUME CHANGES AFTER NOURISHMENT

The volume changes of sand for the nourished beach are computed by adding
the volume changes of sand in every two adjacent profiles between the July and
November surveys. In computing the volume change between any two adjacent
profiles, the volume change per beach length at each profile is first calculated. This
is equivalent to computing the area change of sand in a profile between the July and
November surveys. The individual profile area is obtained by using a trapezoidal
rule to numerically integrate the area from the monument to a reference offshore
distance, which is normally chosen at the place where the water depth is equal
to 12 feet. The volume change in any two adjacent profile lines is computed,
based on the spacings between the two profiles, and using the trapezoidal rule.
A positive change of volume corresponds to the increase of volume and indicates
a convergence zone of sand, while a negative change of volume corresponds to
the decrease of sand and a divergence zone. Table 2 presents the results for the
computation of volume changes from profiles R-96 to R-111G between the July
and November surveys. The integration of sand area in a profile is referred to
N.G.V.D, 1929, and is carried out from the monument location to a 12 feet depth
offshore distance.

a profile into one single profile. The reduced data indicate the final form for the
surveyed profiles and are available in 5.25" floppy diskettes at the Department of
Coastal and Oceanographic Engineering, University of Florida.

Appendix I presents plots combining the offshore profiles and beach profiles,
surveyed by the Department of Geology, University of South Florida, for the post-
nourishment survey. Appendix II presents the offshore and beach profiles for both
the first (July 88) and second (Nov 88) post-nourishment surveys. Some of the
composite profiles are seen to have a segment which is dashed in the nearshore
area. The dashed line indicates the 'constructed' profile which is not available
from either the beach/nearshore profile survey or the offshore profile survey. It is
constructed in a sense that if no bar formation is present in the adjacent profiles
a simple interpolation is then inserted for the gap. Otherwise, a smoothed bar
segment similar to the neighboring profiles is established in the gap. The offshore
profile for R-96 was not measured for this post-nourishment survey and was taken
as the same as the one surveyed in January, 1989. The comparison of profiles
T-104 between July and November surveys reveals large deviation of the two for
offshore distances greater than 2,600 feet. It is noted here that offshore portion
of T-104 was not measured in July, and it was linearly interpolated between the
two adjacent profiles: R-103A and T-104A. Thus, the interpolated T-104 profile
of July is less accurate than the measured one of November.

CALCULATION OF VOLUME CHANGES AFTER NOURISHMENT

The volume changes of sand for the nourished beach are computed by adding
the volume changes of sand in every two adjacent profiles between the July and
November surveys. In computing the volume change between any two adjacent
profiles, the volume change per beach length at each profile is first calculated. This
is equivalent to computing the area change of sand in a profile between the July and
November surveys. The individual profile area is obtained by using a trapezoidal
rule to numerically integrate the area from the monument to a reference offshore
distance, which is normally chosen at the place where the water depth is equal
to 12 feet. The volume change in any two adjacent profile lines is computed,
based on the spacings between the two profiles, and using the trapezoidal rule.
A positive change of volume corresponds to the increase of volume and indicates
a convergence zone of sand, while a negative change of volume corresponds to
the decrease of sand and a divergence zone. Table 2 presents the results for the
computation of volume changes from profiles R-96 to R-111G between the July
and November surveys. The integration of sand area in a profile is referred to
N.G.V.D, 1929, and is carried out from the monument location to a 12 feet depth
offshore distance.

* nourished area from R-99G to R-107
** horizontal distance over which volume is integrated (from baseline
to an approximate depth of 12 ft)
***volume relative to N.G.V.D. 1929

Figure 2 shows the computed volume changes and cumulative changes between
profiles R-96 and R-111G. It is seen in Figure 2 that the greatest volume losses
occur in two areas: one is between R-99G and T-100A, and another is between
T-104A and R-107. It appears that the volumetric changes shown in the lower
part of Figure 2 are primarily due to a combination of three effects: (1) the ex-
pected "spreading" losses associated with the nourishment project, (2) trapping of
northerly transport by the Redington Shores breakwater, and (3) the background
erosion.

The total calculated volume loss of sand in the nourished segment (from R-
99G to R-107) between the July and November surveys is 49,215 cubic yards,
which is a loss of about 9.3 percent of 529,150 cubic yards actually placed in the
nourishment project. However, most of the lost volume of sand is found to stay in
the neighbourhood inside the entire survey region. The total loss of sand computed
between R-96 and R-111G is 18,305 cubic yards, which is only 3.5 percent of the
sand placed in the nourishment project. It is stressed that a part of these net
volume reductions is due to the background erosion and not due to spreading
losses induced by the nourishment project.

WAVE DATA

The wave data were collected by a UF maintained underwater wave gage lo-
cated about 3 miles offshore Clearwater Beach, Florida. The data contain uni-
directional wave information, including modal wave period and significant wave
height. The directional wave gage is scheduled to replace the unidirectional gage
in and after the third quarter monitoring period. Until the directional wave gage
is available in collecting wave data, wave directions are assumed to be the same
as the local wind directions. Appendix III presents the wave data collected in Au-
gust, September, October, November, 1988. The gage was not operable between
Sep 24 and Oct 11, and between Oct 29 and Nov 20. The wave refraction analysis
is in process and will be presented as an addendum to this report.

Figure 2 shows the computed volume changes and cumulative changes between
profiles R-96 and R-111G. It is seen in Figure 2 that the greatest volume losses
occur in two areas: one is between R-99G and T-100A, and another is between
T-104A and R-107. It appears that the volumetric changes shown in the lower
part of Figure 2 are primarily due to a combination of three effects: (1) the ex-
pected "spreading" losses associated with the nourishment project, (2) trapping of
northerly transport by the Redington Shores breakwater, and (3) the background
erosion.

The total calculated volume loss of sand in the nourished segment (from R-
99G to R-107) between the July and November surveys is 49,215 cubic yards,
which is a loss of about 9.3 percent of 529,150 cubic yards actually placed in the
nourishment project. However, most of the lost volume of sand is found to stay in
the neighbourhood inside the entire survey region. The total loss of sand computed
between R-96 and R-111G is 18,305 cubic yards, which is only 3.5 percent of the
sand placed in the nourishment project. It is stressed that a part of these net
volume reductions is due to the background erosion and not due to spreading
losses induced by the nourishment project.

WAVE DATA

The wave data were collected by a UF maintained underwater wave gage lo-
cated about 3 miles offshore Clearwater Beach, Florida. The data contain uni-
directional wave information, including modal wave period and significant wave
height. The directional wave gage is scheduled to replace the unidirectional gage
in and after the third quarter monitoring period. Until the directional wave gage
is available in collecting wave data, wave directions are assumed to be the same
as the local wind directions. Appendix III presents the wave data collected in Au-
gust, September, October, November, 1988. The gage was not operable between
Sep 24 and Oct 11, and between Oct 29 and Nov 20. The wave refraction analysis
is in process and will be presented as an addendum to this report.

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